Apparatuses for determining whether a substance is carried in a fluid

Apparatuses for determining whether a substance is carried in a fluid are disclosed. One such apparatus includes a body having: a plurality of spaced-apart capture surfaces configured to contact the fluid and capture the substance from the fluid; and a plurality of fluid guiding surfaces spaced apart by a predetermined distance from respective at least portions of respective ones of the plurality of capture surfaces. Another such apparatus includes: a fluid conduit to direct flow of the fluid; and at least one element removably positioned in the fluid conduit and having at least one capture surface configured to contact the fluid and capture the substance from the fluid.